WO2009141268A1

WO2009141268A1 - Piston for a brake calliper

Info

Publication number: WO2009141268A1
Application number: PCT/EP2009/055876
Authority: WO
Inventors: Dirk Koch; Thomas Winkler; Anja Klimt; Herwig Bauer
Original assignee: Continental Teves Ag & Co. Ohg
Priority date: 2008-05-21
Filing date: 2009-05-14
Publication date: 2009-11-26
Also published as: DE102009019662A1

Abstract

The invention relates to a piston (1) for a brake calliper of a partially lined disc brake. The piston comprises a support (2) made of plastic material and a cup-shaped metallic insert (13). According to the invention, the insert (13) comprises a peripheral flange (14) that rests against an end surface (10) of the plastic part, and the flange (14) is bonded to the end surface (10) of the plastic part in hydraulically sealed fashion.

Description

Piston for a caliper

The invention relates to a piston for a caliper of a partially lined disc brake according to the preamble of patent claim 1.

By way of example, DE 195 34 220 A1 discloses a cup-shaped piston made of plastic material. The piston comprises a bottom and a cylindrical wall whose open end face acts on a friction lining. This known piston made of plastic material is designed to be particularly stress-resistant and endures occurring mechanical compressive stresses in principle without metallic reinforcement by a disk-shaped and therefore high-strength soil always remains in a receiving bore from the caliper, even if brake pads and brake disc are extremely worn. The wall is essentially stressed exclusively by compressive stress. In a variant of this document, an insert is provided which is inserted into the unwetted, fluid-free pot interior of the piston, and overlaps an opposite end face of the wall. This arrangement serves in the known piston the purpose of providing a thermal coupling. In other words, the usually bakelitartig formed plastic material is a poor thermal conductor, and this thermal insulation effect of the plastic material is avoided by the metallic insert by the frictional heat is transmitted from the friction lining on the insert on the brake fluid.

However, modern vehicle brake systems provide spindle drives in the caliper housing that are suitable for wear adjustment or for can serve an electromechanical actuation. In principle, it is conceivable in principle to arrange a pot-shaped piston in the caliper so that the pot interior is acted upon by brake fluid, and that the closed bottom acts on the friction lining. However, this increasingly tensile and bending stresses are introduced into the piston. Although it has been found that the material characteristics of plastic materials are fundamentally suitable for application of axial force, internal compressive stress in the thin tensile stress compressive stress is not readily suitable for this type of stress, so that the proposal has already been made to provide a punctual mechanical reinforcement of metal material.

However, an intimate and permanent connection between plastic material and metal material, in particular steel or aluminum, not without problems, because these materials have completely different coefficients of thermal expansion. Because a vehicle brake is subjected to extreme weathering, extreme temperature changes and in addition to varying hydraulic pressure, in the present case a piston with particular protection against delamination is proposed.

It is therefore an object of the invention to propose a piston using plastic material with a metallic insert, which is designed in accordance with stress, and whose construction is particularly protected against delamination.

The object of the invention is achieved by the characterizing features of independent claim 1. Accordingly, the insert has a right angle to a piston axis arranged, circumferential, flange, and wherein between the flange and the end face is arranged a right angle to the piston axis arranged sealing joint. Preferably, the flange is provided with an adhesive bonded to the end face of the piston. By at least slightly more metal material is provided by the flange according to the invention at the cylindrical, open end, in a bending-critical zone of the piston, the piston is stiffened by increasing the resistance moment. In addition, the parting line between the plastic part and insert against delamination is protected by this is hidden by radial arrangement provided. The delamination due to the hydraulic pressure is also avoided because the pressure primarily causes a reinforced system between the wall and flange.

In the end face can be provided in an advantageous embodiment, a groove for receiving the at least one sealing means. This makes it possible, for example, to arrange the sealant, respectively the adhesive prior to assembly of the components involved. It is understood that the sealing agent or the adhesive may in principle be provided as a solid shaped body such as in particular as an O-ring or as a solid adhesive in O-ring form, without departing from the invention.

For a complete sealing of the sealing joint, the groove has a semicircular cross-section. Furthermore, this groove is provided at least approximately centrally placed to the sealing joint.

The end face is graduated at least slightly on the order of its cross-sectional thickness for a recessed recording of the flange, which shortens the axial length. It is advantageous if the insert on an axial force-transmitting surface for interaction with a corresponding surface of the spindle device is butted and / or flat and / or spherical.

An effective production is achieved when the bottom and wall are made of plastic, that the insert of metallic sheet material is formed as a deep-drawn component, and wherein a minimum wall thickness of the wall is dimensioned such that it is at least about several times the cross-sectional thickness of the insert.

A particularly production-oriented rotation lock is made possible when the insert has a parallel to the piston axis extending key surface and or a polygon such as in particular a hexagonal key surface for the positive reception of a threaded nut. Such a profiling has the additional advantage that the bending resistance torque is increased.

Other features, advantages and applications of the invention will become apparent from the following description with reference to two embodiments according to the drawing.

In the drawing shows:

Fig. Ia and Ib a first embodiment of a piston according to the invention in longitudinal section and an enlarged section and

Fig. 2 shows a second embodiment of a piston according to the invention in longitudinal section.

Fig. 1 illustrates a weight-optimized piston 1 comprising a support 2 of at least partially Plastic material is formed, and parallel to a piston axis 3 slidably received in a receiving bore 4 of a metallic caliper 5. The caliper 5 is part of a disc brake, which is hydraulically, mechanically or electromechanically actuated. In this case, the carrier 2 is generally designed as a cup-shaped hollow cylinder open on one side, which comprises a disk-shaped, largely flat base 6. Integral to the bottom 6, a wall 7 is provided, the outer circumference 8 serves to guide within the receiving bore 4. For the purpose of sealing, a not further clarified seal can be provided in the receiving bore 4. In the drawing, a particularly critical, widely extended operating position of the piston 1 is illustrated. In the transition region between the bottom 6 and the wall 7, a groove 9 is integrated into the wall 7 radially outward, which serves to receive a so-called, not shown, protective cap. At the end of the wall 7, this has an end face 10, which runs essentially parallel to the bottom 6. By such a construction, a pot inner 11 is hydraulically acted upon by brake pressure, so that an outwardly directed contact surface 12 from the bottom 6 against a back plate of a friction lining 19 can be pressed, which acts on a disc 20. This basic mode of action is essentially the same for both mechanical / hydraulic and electromechanical actuation. In the inner pot 11 of the piston 1 takes a substantially cup-shaped, advantageously multi-stepped, metallic insert 13 and particularly preferably in addition to a spindle device, not shown, which serves the Reibbelagverschleißkompensation or a parking brake mechanism. The insert 13 is basically incorporated in the brake actuation force flow, and is applied starting from the interior of the pot 11 by the pressure medium. At right angles to the piston axis 3, the insert 13 an annular peripheral flange 14. By the flange 14, the end face 10 of the wall 7 at least partially overlaps, and rests on the end face 10, a right angle to the piston axis 3 arranged sealing joint 15 is made possible. At the same time, the flange 14 increases the rigidity of the piston 1 by its resistance torque is increased in a particularly high stress area at the open, free end. Consequently, a stress-based design results. The hydraulic pressure force primarily causes the sealing joint 15 is positively closed, with this advantageous effect even increases with increasing pressure. As a result, delamination between the carrier 2 and insert 13 is avoided.

In the region of the sealing joint 15, a circular circumferential groove 16 for receiving at least one sealant is incorporated into the end face 10 of the wall 7. In this case, the groove 16 according to the embodiment has a semicircularly rounded cross-section, so that no damage is to be expected even when using rubber-elastic O-ring sealing elements. The groove 16 is basically placed approximately centrally to the sealing joint 15, which corresponds approximately to a mean diameter dm of the flange 14.

As a sealing element in the context of the application is generally also an adhesive to understand that is introduced into the groove 16 and into the sealing joint 15 in order to produce the most intimate, permanent attachment between the carrier 2 and insert 13. It is further understood that a plurality of sealing elements or adhesives can be used side by side. It is further understood that the one or more sealing sections need not be placed exclusively in the region of the sealing joint 15, but be provided in an entire joint between the carrier 2 and insert 13 can .

For a recessed arrangement of the insert 13, the end face 10 of the wall 7 is stepped, which reduces the axial length of the piston 1. For this countersunk recording of the flange 14, the necessary step height is at least approximately of the order of the cross-sectional thickness t of the insert 13. If the insert 13 is stepped, or has no uniform thickness t, the cross-sectional thickness in the region of the flange 14 is relevant.

As already indicated, the insert 13 is integrated in the power flow of the actuator. To accommodate geared actuators with spindle-nut drive (electromechanical brake actuators, friction pad compensation devices), the insert 13 has at least one axial force transmitting surface 17 for co-operation with a corresponding surface of a non-illustrated threaded spindle or nut of the spindle nut drive. For this purpose, the surface 17 is tapered and / or plan and / or spherical, wherein a spherical shape acts self-centering.

For manufacturing fair, durable and weight-optimized design of the components contributes that bottom 6 and 7 wall are formed of plastic carrier 2, that the insert 13 is formed of metallic sheet metal as a deep-drawn component, and wherein a minimum wall thickness d of the wall 7 is dimensioned in that it is at least about a multiple of the cross-sectional thickness t of the insert 13. As a result, the invention is primarily suitable for piston series with a large outer diameter, which normally consist entirely of metal material. The insert 13 furthermore comprises a radially inner receptacle 18, arranged in an enlarged diameter area, for a threaded nut (not shown), wherein an anti-twist protection is realized in that the receptacle 18 has an integrated key area and / or a polygon, in particular a hexagon key area for the positive reception 18 has a correspondingly shaped outer contour of the threaded nut. This profiling additionally supports the strength of the piston 1 because its resistance moment is increased.

The piston 1 according to the invention has a low weight through the use of plastic, and its pot inner 11 can still be used variably. The metallic insert 13, which can absorb both tensile and compressive stresses, allows the smallest possible wall thickness d from the carrier 2, without fear of delamination and destruction of the components involved

LIST OF REFERENCE NUMBERS

1 piston

2 carriers

3 piston axis

4 receiving hole

5 caliper

6 floor

7 wall

8 outer circumference

9 groove

10 face

11 pot inside

12 contact surface

13 use

14 flange

15 sealing joint

16 groove

17 area

18 recording

19 friction lining

20 disc

Claims

claims

1. Piston (1) for a brake caliper (5) of a hydraulically and / or mechanically and / or electromechanically operable disc brake, which is designed substantially as a unilaterally open cup-shaped hollow cylinder, and a bottom (6) and an integrally on the bottom (6 ) arranged wall (7) and comprising a groove (9) in the transition between the bottom (6) and wall (7), and a parallel to the bottom (6) arranged end face

(10), wherein the bottom (6), starting from the inside of the pot (11) can be acted upon with brake pressure, so that an outwardly directed contact surface (12) against a friction lining (19) can be pressed, wherein the interior of the pot

(11) accommodates a metallic insert (13 and preferably a spindle device, which can be inserted into a power flow of a parking brake mechanism, characterized in that the insert (13) has a peripheral flange (14) arranged at right angles to a piston axis (3). and wherein between the flange (14) and end face (10) a right angle to the piston axis (3) arranged sealing joint (15) is provided.

2. Piston according to claim 1, characterized in that the

End face (10) has a groove (16) for receiving at least one sealing means.

3. Piston according to claim 2, characterized in that the

Groove (16) has a semicircular cross-section, and that the groove (16) is placed at least approximately centrally of the sealing joint (15).

4. Piston according to claim 1, characterized in that the

End face (10) for a recessed receptacle from the flange (14) at least somewhat graduated in the order of its cross-sectional thickness (t) is formed.

5. Piston according to claim 1, characterized in that the

Insert (13) has a separate circumferential surface (17) for cooperation with a corresponding surface of the spindle device, and that the surface (17) is tapered and / or planar and / or spherical.

6. Piston according to claim 1, characterized in that the ground

(6) and wall (7) are formed of plastic, that the insert (13) is formed of metallic sheet metal material as a deep-drawn component, and wherein a smallest wall thickness (d) of the wall (7) is dimensioned such that these at least about a multiple of the cross-sectional thickness (t) of the insert (13).

7. Piston according to at least one of claims 1 to 6, characterized in that the insert (13) is stepped, and a receptacle (18) with a key surface and / or a polygon, in particular a hexagonal key surface for the positive reception of a threaded nut having.